Natural Convection Heat Transfer in the Horizontal Dry Storage System for the LWR Spent Fuel Assemblies

Abstract

A heat transfer and flow visualization experiment was conducted with a one-fifth scale model simulating a dry shielded canister (DSC) with 24 PWR spent fuel assemblies in order to elucidate the heat transfer characteristics and the velocity distribution for natural convection inside a DSC filled with air or water at atmospheric pressure. It was found that the average heat transfer coefficients were proportional to the onefourth power of the Rayleigh number despite the complicated geometry inside the DSC. Flow patterns inside the DSC were visualized clearly through a digital image processing system. The velocity distributions inside the DSC were obtained quantitatively from the Particle Tracking Velocimetry. In comparison with the results of a two-dimentional thermal hydraulic analysis, computed flow patterns were similar to the experimental results and the computational temperature distributions on the sleeve surfaces agreed well with the experiments within S%, except at the top point of the center gap. It was also found that the difference in the heat transfer coefficient was within 25% for air as the working fluid, while a satisfactory agreement was not obtained when water was the working fluid.

Thermal modeling of a vertical dry storage cask for used nuclear fuel

“…Herewith, we will briefly review recent studies on heat transfer in a full fuel storage cask that are publically accessible. Nishimura (1996) [8] experimentally and numerically (using ZEPHYRUS code) investigated natural convection heat transfer in a horizontal storage cask containing 24 electrically heated dummy fuel assemblies that used air or water as the cooling media. This experimental cask is a 1/5 scale model of the actual dry shielded canister in which Rayleigh number (Ra, based on inner radius of the canister) varies from 3x10 7 to 2x10 8 .…”

Thermal analysis of a spent fuel cask in different transport conditions

“…Moreover the convective coefficient values were considered negligible for air or water in the hypothesis of the absence of fluid turbulence inside the cask [11,12], while those representative of heat transfer mode between the impact limiters-cask or the cooling fins surfaces and the external environment was assumed in according to Eqs. (1) and (2) (experimental correlation [13]):…”

Modeling of ATR fuel in DOE Standard Canisters with Helium Backfilled Condition

“…The flow in storage containers of spent nuclear fuel is primary driven through natural convection as air is heated from the central fuel and cooled by the outer air, shown both experimentally and in numerical computational fluid dynamics (CFD) simulations (Nishimura et al 1996;Lee et al 2000;Lee et al 2013;Heng et al 2002;Brewster 2012 et al;Bang et al 2015;Jeong et al 2016;Smith 2016). Improvements to basic models have used commercial packages to fully resolve the fuel configurations in lieu of coarse-resolution porous media models (Brewster et al 2012).…”